Have you received the interest yet?

I don't presume anything as far SS are concerned, ie if you choose 2 dates and there is no payment date within you just get a string of  0's!!!!!!

Surely if you are operating a Company then you simply accrue the interest to the end of the accounting period?

Actually I think 0risk is right. Interest is calculated on each loan part separately at the end of each month and rounded to the nearest penny. I think if anyone used a bot to actually do this they would get banned pretty quickly.

Exactly. My company has worked in that way for many years and there has never been an issue.  In the days of long term bonds (and similar) I used these to move 'income' into future years.  To an extent this still applies to some P2P/P2B loans where interest is paid at term. The 68% default interest was exactly the case that caused me to question my accounting practices again with my accountants.

As I said, it is easily sorted at my end to take a consistent approach but if you are cash accounting strictly speaking the interest wasn't physically paid until October so should be in next years accounts ...... but the account downloadable statements state it was paid in September (and before a new loan went live) - I certainly couldn't have withdrawn it on the 30th but it now shows that I had that amount in credit ..... and then depending on the time of the day that you download a Tax Statement you can 'chose' what amount you want to be shown 

Interesting advice from your accountant.  Under UK company law, UK statutory accounts must be prepared under under either International Financial Reporting Standards ("IFRS") or UK Generally Accepted Accounting Practice ("UK GAAP").  One of the fundamental principals underpinning IFRS and UK GAAP (and most modern accounting practices) is the use of accruals basis of accounting.  Interest should always be accounted on an accruals basis (rather than a cash basis) in UK statutory accounts.  However, if differences are not significant, you can state you use a compliant accrual accounting policy, but still give the cash accounting figure on the basis that it is not materially different (and thus materially correct).  It would be unusual to actually state in the accounts that you are using a cash accounting policy as this would be non-compliant with either IFRS or UK GAAP and you would be obliged to explain this non-compliance and effectively highlight that the accounts are unlawful.  The only lawful reason for not being compliant with either set of accounting standards is if compliance would not result in the accounts presenting a 'true and fair view', often referred to as the true and fair override.  There are very limited instances of such override being used.  

Tax is based on statutory accounts after certain tax adjustments (eg treatment of capital expenditure etc) and thus tax on interest is normally on an accruals basis.  However, since 2013, small unincorporated businesses (ie sole traders and general partnerships comprising of individuals) have been allowed to prepare tax accounts on a cash basis (as it is simpler and more widely understood).  Unincorporated entities are not subject to the Companies Act and are not required to prepare statutory accounts, with their financial reporting requirements being those specified by HMRC under tax law (which generally states that these have to be prepared under UK GAAP with exceptions such as this one).

The above analysis is probably completely OTT given that the difference between the accrual and cash value of interest reported for any 12 month period is unlikely to material for the full year figure (as you are probably still capturing 12 months interest with only a small cut-off error at the start and end of the period), but I did find it curious that you would actually state that you use cash accounting in your statutory accounts.

I think you'd need 51p to get 1p of interest in a 30 days month.

BTW, did you make your spreadsheet available for download?